1. Field of the Invention
The present invention relates generally to the field of communication. More particularly, the present invention relates to method and system for transmitting data, based on deterministic quality of service by one or more devices in a communication network.
2. Description of the Related Art
In a communication system, data transfer between a plurality of devices involves a wired or wireless medium. The Institute of Electrical and Electronics Engineers (IEEE) 802.11 Medium Access Control (MAC) protocol supports the contention based access of the wireless communication medium. In contention based access, multiple devices that need to communicate contend to access the wireless medium. Further, the IEEE 802.11 protocol follows a law of priority, where the transmission of traffic types with higher priority levels is prioritized over the transmission of traffic types with lower priority levels. Here, the traffic types with a lower priority level do a back-off for a random period of time before trying to access the wireless medium again. “Back-off” refers to the storing of data, in a MAC layer, to be retransmitted due to heavy traffic. The period of time for which the traffic types with lower priority levels back-off can be referred to as a back-off value. The lower priority transmissions wait for the wireless medium to become clear. Each time access is denied, back-off occurs for a longer time period until a pre-defined back-off value is reached.
In order to cater to various traffic types such as voice, audio, video and interrupt without affecting the contention based access, Quality of Service (QoS) mechanisms are introduced in wireless communication. A QoS mechanism called Enhanced Distributed Channel Access (EDCA) is widely used on wireless communication systems. According to EDCA, separate priority queues are defined for each of the traffic types. High priority traffic waits less than low priority traffic. Each priority has a different back-off value. The higher the priority order, the shorter the back-off value. EDCA is applicable to infrastructure mode as well as the Wi-Fi P2P direct mode of operation.
The occurrence of back-off is non-deterministic in EDCA. Because the data transfer based on EDCA does not consider the channel availability and buffer status, a non-deterministic QoS results due to back-off of low priority data in a random manner without any specified time constraints. This creates randomness in the time of transmission by delaying the data transmission without a specific time interval due to bad channel quality and reduced wireless medium availability. This affects QoS and communication adversely. For example, in case of applications, such as docking, involving a high rate of data transmission within a short distance, the random transfer of higher priority data and lower priority data between the peripheral devices does not meet the required QoS for the peripheral devices because of non-deterministic back-off.